This invention relates to sewing machines and, more particularly, to sewing machines having positional coordinates for successive stitch penetrations stored in a memory. Specifically, this invention relates to the alteration of such positional coordinates, under operator command, during the formation of a buttonhole pattern so as to selectively vary the width of the buttonhole pattern cutting space while maintaining constant the overall buttonhole pattern width.
A sewing machine is disclosed in copending U.S. patent application Ser. No. 928,940, filed on even date herewith by the applicants herein, and assigned to the assignee of the present invention, wherein the positional coordinates for successive stitch penetrations are stored in a memory having addressable locations corresponding to a plurality of operator selectable patterns. Means are provided for operator initiation of an override command to selectively alter the operation of the feed and bight actuators to an amount of motion different from that dictated by the stored pattern information. An operator influenced control provides a digital signal corresponding to a desired alteration value. Override memory locations are provided for storing bight and feed actuator motion alteration values. These locations are addressed in accordance with the selected pattern and the digital override signal provided by the operator. The alteration values are utilized for control of the appropriate feed and bight actuators. One of the operator selectable patterns is a buttonhole pattern. In many instances, it is desirable to vary the buttonhole pattern cutting space while maintaining constant the overall buttonhole pattern width. Such is not possible with the arrangement disclosed in the aforereferenced application because in the system disclosed therein the alteration values are applied to every stitch within a selected pattern.
It is therefore an object of the present invention to provide a sewing machine having buttonhole pattern sewing capability wherein the width of the cutting space may be selectively varied while maintaining constant the overall buttonhole pattern width.